WASHINGTON — The sudden departure of the Justice Department’s No. 3 official is adding to the turmoil at an agency that already lacks permanent, politically appointed leaders for many of its most important divisions.

Associate Attorney General Rachel Brand’s resignation builds on an unusual problem that has contributed to instability in the department, current and former officials say, and has prevented the Trump administration from fully implementing its agenda more than a year after Attorney General Jeff Sessions took office.

Sessions lamented situation Monday, blaming a single Republican senator for holding up the confirmations of key figures, including the heads of the department’s national security, criminal and civil rights divisions. While not mentioning him by name, Sessions left no doubt he was referring to Sen. Cory Gardner of Colorado, who promised to prevent the confirmation of all Justice Department nominees after Sessions lifted Obama-era protections for states that have legalized marijuana.

There’s no progress reported in talks between Colorado’s Republican senator and the Republican Attorney General over marijuana policy.

Sen. Cory Gardner met with Attorney General Jeff Sessions on Wednesday. Last week Sessions removed Obama-era protections for states like Colorado with legalized marijuana. Gardner acted to prevent confirmation of all nominees to the Department of Justice unless Sessions reversed himself.